Lung Malformations & Diaphragmatic Hernia

1. Congenital Lobar Emphysema (CLE)

Definition & Pathogenesis

• Intrinsic bronchial cartilage defect → dynamic airway collapse and air trapping (up to 25% of cases)
• Polyalveolar theory (Hislop & Reid, 1970) — a fivefold increase in the number of normal-sized alveoli ("alveolar giantism") without overdistension
• Extrinsic compression by aberrant vessels or masses causing unilateral lobar hyperinflation

Clinical Presentation

• Most cases present in the first 6 months of life with cough, respiratory distress, wheezing, retractions, and cyanosis
• Physical exam: diminished breath sounds on the affected side, mediastinal shift
• Some cases go undiagnosed until adulthood (incidental finding)
• Positive pressure ventilation must be used cautiously — high risk of auto-PEEP

Diagnosis

• Chest X-ray: focal lobar hyperlucency with contralateral mediastinal shift; bronchovascular markings within the lucent area help distinguish CLE from pneumothorax or a cyst
• CT chest: focal lobar overdistension, pulmonary vessels traversing the lobe, compressive atelectasis of adjacent lung; rarely, herniation to the contralateral side
• V/Q scan: reduced ventilation and perfusion to the affected lobe (used in surgical planning)
• Pulmonary function tests often normal; reduced FVC and FEV in severe cases

Treatment

• Asymptomatic / mildly symptomatic: conservative management with close follow-up
• Respiratory distress with mediastinal shift: expeditious open lobectomy is indicated
• This condition is potentially reversible if diagnosed and treated in a timely manner

2. Lung Cysts

Bronchogenic Cysts

• Early budding → cysts near the carina and right hilum (mediastinal)
• Later budding → more peripheral, intrapulmonary

Clinical Presentation

• Often asymptomatic (incidental finding)
• Compression of mediastinal structures → superior vena cava syndrome, dysphagia, dyspnea
• Infection of the cyst (82% of symptomatic cases) → chronic cough, purulent expectoration, recurrent fever, chest pain, hemoptysis
• Postobstructive pneumonia

Diagnosis

• Chest X-ray: ovoid parenchymal structure with sharp borders; air-fluid level if infected
• CT chest (modality of choice): water-to-soft-tissue density, no contrast enhancement; may contain "milk of calcium" (calcium precipitate)
• MRI: variable T1 signal (depends on protein content); high T2 signal
• Histopathology of resected specimen: definitive diagnosis
• Differential: hydatid cyst (septations), cystic teratoma (fat, anterior mediastinum), lung abscess

Treatment

• Asymptomatic: conservative management; mediastinoscopy/TBNA may be done for diagnosis
• Symptomatic: surgical excision
  • VATS is the treatment of choice for accessible cysts
  • Posterolateral thoracotomy for large, complicated cysts
  • Bronchoscopic drainage (transbronchial) is a less invasive option for mediastinal cysts

Congenital Pulmonary Airway Malformation (CPAM/CCAM)

3. Spontaneous Pneumothorax

Classification

• No underlying lung disease
• Most common cause: rupture of an apical subpleural bleb
• Etiology of blebs unknown; more frequent in smokers, tall thin young males
• Recurrence rate: ~30% after first episode

• Occurs with underlying lung disease: emphysema (bleb/bulla rupture), cystic fibrosis, AIDS, metastatic sarcoma, asthma, lung abscess, lung cancer, LAM (lymphangioleiomyomatosis), endometriosis (catamenial pneumothorax — occurs within 72 hours of onset of menses)

Clinical Presentation

• Sudden-onset pleuritic chest pain and dyspnea
• Decreased or absent breath sounds on the affected side
• Hyperresonance to percussion
• Tracheal deviation (tension pneumothorax)

Diagnosis

• Chest X-ray: absent lung markings with visible pleural line; mediastinal shift in tension
• CT chest: identifies blebs/bullae and guides surgical planning; also useful when CXR is equivocal
• Thoracoscopy: identifies underlying lesions (blebs/bullae) in ~70% of cases; both diagnostic and therapeutic

Treatment

• Talc poudrage (thoracoscopic): recurrence rate ~5%; highly effective, cost-effective; may minimally reduce TLC long-term but clinically unimportant
• VATS + mechanical abrasion/pleurectomy: recurrence ~1.8% when talc added; higher if bulectomy alone (27.5% at 10 years)
• Talc pleurodesis is not an absolute contraindication to future lung transplantation

• Catamenial pneumothorax: pleurodesis + hormonal therapy
• LAM: pleurodesis recommended after first episode (>70% recurrence risk)
• Occupational hazards (air travel, scuba diving): lower threshold for surgical intervention

4. Pulmonary Sequestration

1. No connection to the airway/tracheobronchial tree
2. Aberrant systemic arterial supply (thoracic aorta 75%, abdominal aorta 25%)

Types

Clinical Presentation

• Most cases asymptomatic at birth
• ILS: recurrent lower respiratory tract infections → most common presentation; often diagnosed in adolescence/adulthood; up to 50% of adults asymptomatic
• ELS: usually asymptomatic; rarely — GI fistula (air/air-fluid level on imaging)
• Prenatal: identified on second-trimester ultrasound as solid, echogenic, well-defined mass; color Doppler shows systemic feeding artery

Diagnosis

• Prenatal ultrasound + color Doppler: identifies systemic feeding artery (characteristic)
• CT chest with angiography (adults — modality of choice): consolidation/mass ± cystic changes predominantly in left lower hemithorax with identifiable feeding artery
• MRI: homogenous mass, high T2 signal vs. lung; lower than amniotic fluid
• CXR: intralobar — non-specific consolidation; extralobar — soft tissue mass separate from lung

• 71% intralobar and 94% extralobar BPS decrease in size or regress before birth

Treatment

• Asymptomatic, small BPS: conservative management with serial imaging
• Symptomatic / larger lesions: surgical resection at 6–12 months of postnatal life
  • ILS: segmentectomy or lobectomy (VATS or open)
  • ELS: mass resection
• Adults: most common indication is recurrent infection; VATS preferred
• Antenatal: intrafetal vascular laser ablation of feeding artery (emerging; 92% reduction/resolution in small series)
• Prenatal spontaneous regression occurs in >2/3 of prenatally diagnosed lesions

5. Congenital Diaphragmatic Hernia (CDH)

Epidemiology & Anatomy

• Incidence: 1:2,000–5,000 live births; mostly sporadic and non-syndromic
• Bochdalek hernia (posterolateral): 70–75% of CDH; left-sided 85%, right 13%, bilateral 2%
• Morgagni hernia (anterior): 23–28% — usually asymptomatic in infancy, diagnosed later in childhood
• Central hernia: 2–7%
• Isolated CDH in 60%; if associated anomalies, mortality >85%

Pathophysiology

• Bilateral pulmonary hypoplasia (ipsilateral > contralateral): fewer airway branches, reduced alveolar surface
• Pulmonary hypertension: increased arteriolar smooth muscle thickness; hypersensitivity to vasoactive factors
• Reduced lung compliance; right-to-left shunting

Clinical Presentation

• Diagnosed by ultrasound in ~2/3 of cases (as early as 15 weeks)
• Ultrasound findings: mediastinal shift, abdominal viscera in thorax, gastric bubble in chest, polyhydramnios, cardiac compression
• Left CDH: rightward heart/mediastinal shift; stomach/intestines in left chest
• Right CDH: leftward shift with liver in right chest (harder to diagnose — liver echogenicity similar to fetal lung)

• Respiratory distress at birth: grunting, dyspnea, retractions, cyanosis
• Scaphoid abdomen (bowel absent from abdomen)
• Diminished breath sounds on the affected side; bowel sounds in chest
• Displaced heart tones
• Pre- and postductal SpO₂ differences indicating right-to-left shunting
• Chest X-ray: intrathoracic bowel loops + mediastinal shift
• Morgagni hernia: often delayed diagnosis (childhood); most infants asymptomatic

Prognostic Assessment

• Lung-to-head ratio (LHR): LHR <1 = poor prognosis; LHR >1.4 = ~100% survival
• Observed/Expected LHR (O/E LHR): <25% → <20% survival
• Liver herniation ("liver up") indicates more severe disease
• Associated anomalies (cardiac, chromosomal trisomies, single gene defects) worsen prognosis

Management

Prenatal Intervention — FETO

• TOTAL trial (severe CDH, O/E LHR <25%): stopped early for efficacy — 40% survival in FETO group vs. 15% in expectant management
• TOTAL trial (moderate CDH): no survival benefit demonstrated
• Currently offered at select fetal centers for severe CDH

Postnatal Initial Stabilization

• Avoid mask ventilation (distends herniated bowel, worsens compression)
• Immediate endotracheal intubation + nasogastric decompression
• Gentle ventilation: limit peak inspiratory pressure, permissive hypercapnia (pH >7.2)
• Pulmonary hypertension management: inhaled NO (iNO), sildenafil, milrinone
• ECMO (extracorporeal membrane oxygenation): bridge to surgery in patients with severe pulmonary hypertension refractory to medical management

Surgical Repair

• Surgery is performed after stabilization (not immediately at birth)
• Approach: transabdominal (laparotomy/laparoscopy) or transthoracic (thoracoscopy)
• Repair of diaphragmatic defect:
  • Primary closure: for small defects
  • Prosthetic patch (polytetrafluoroethylene/Gore-Tex): for large defects — higher recurrence rate (~50%) vs. primary repair
• Abdominal wall closure may require a silo if viscera cannot be replaced without tension
• Survival: 65–90% in current era (improved from earlier decades)

Long-term Morbidity

• Bronchopulmonary dysplasia, persistent pulmonary hypertension
• Gastroesophageal reflux, feeding difficulties
• Thoracic deformity after repair
• Neurodevelopmental sequelae

Key Comparative Summary